When you sit quietly, your heart slips into the slower, steady pace known as your resting heart rate. An increase in your resting heart rate over time may be a signal of heart trouble ahead.

Your heart rate changes from minute to minute. It depends on whether you are standing up or lying down, moving around or sitting still, stressed or relaxed. Your resting heart rate, though, tends to be stable from day to day. The usual range for resting heart rate is anywhere between 60 and 90 beats per minute. Above 90 is considered high.

Many factors influence resting heart rate. Genes play a role. Aging tends to speed it up. Regular exercise tends to slow it down. (In his prime, champion cyclist Lance Armstrong had a resting heart rate of just 32 beats per minute.) Stress, medications, and medical conditions also influence the heart rate.

Results of observational research studies support a link between health and heart rate. Researchers from Norway previously reported the results of a large study looking at changes in resting heart rate over 10 years. They recruited more than 29,000 people without any history or heart disease, high blood pressure, or any other type of cardiovascular disorder, and measured their resting heart rates when they started the study and again 10 years later. This study was published in the Journal of the American Medical Association.

Compared to people whose resting heart rates were under 70 beats per minute at the study’s start and its end, those whose resting heart rate rose from under 70 to more than 85 were 90% more likely to have died during the course of the study. The increase in risk was slightly less for those with resting heart rates of 70 to 85 at the study’s start and who had a greater than 85 at the study’s end.

Although 90% sounds like a huge and scary increase, let me put it in perspective. Among the group whose heart rates stayed under 70 throughout the study, there were 8.2 deaths per 10,000 people per year. Among those whose heart rates rose above 85, there were 17.2 deaths per 10,000 people per year.

The results also suggested that lowering your heart rate over time may be beneficial, but the researchers could not say that for certain.

What this means for you

You don’t need a doctor’s visit to keep track of your resting heart rate. The best time to measure it is before you get out of bed in the morning. You can measure your heart rate at your wrist or neck by placing one or two fingers over a pulse point, counting the number of beats in 15 seconds, and multiplying by four.

By doing these 4 things you can slow your resting heart rate and also help maintain a healthy heart:

Exercise more. When you take a brisk walk, swim, or bicycle, your heart beats faster during the activity and for a short time afterward. But exercising every day gradually slows the resting heart rate.